Cartridge cases



May 15, 1962 K. GRONN CARTRIDGE CASES 2 Sheets-Sheet l Filed March 23, 1959 lrllllllll llllll Illllllii III!! 11i I Illlllll llfllrllllla INVENTOR KARL GRONN BY ATTORNEYS May 15, 1962 K. GRONN CARTRIDGE cAsEs 2 Sheets-Sheet 2 Filed March 23, 1959 ffy. 4.

IN VEN TOR KARL GRONN B ATTORNEYS 3,34A33 Patented May 1K5, 1962 tice 3,034,433 CARTRIDGE CASES Karl Gronn, Wergelandsvn. 5, Oslo, Norway Filed Mar. 23, 1959, Ser. No. 801,190 Claims priority, application Norway Nov. 3, 1958 Z Claims. (Cl. Q-43) The usual cartridge cases of brass have the drawback of being relatively expensive, partly on account of the price of the material, partly on account of the material being relatively diicult to work. Therefore, it has been attempted to employ other materials for producing'cartridge cases. For instance, it has been suggested to produce cartridge cases of light metal in the conventional manner. However, such cartridge cases have such substantial drawbacks that their use in actual practice is prevented. For instance, such cartridge Vcases are more expensive than the brass cases. Cartridge cases of light metal are liable to fasten in the cartridge chamber of the firearm, partly due to the fact that the material has insuliicient elasticity so that the cartridge cases are expanded permanently by the shot and thereby are jammed tight in the cartridge chamber, partly because light metal under heat influence has a very strong adhesion to steel. These circumstances in connection with the insuiicient strength of the material can give rise to tearing off of the cartridge flange, which is one of the most time-consuming function faults in automatic firearms. vIt has been attempted to remedy this drawback by making the end or bottom piece of the cartridge case of for instance brass or steel and providing it with a tubular extension upon which a light metal sleeve is shrinked or rolled. However, hereby it has not been possible to prevent the cartridge case from fastening in the cartridge chamber.

Cartridge cases have also been made of so called plastics, for instance synthetic resin materials, however with a bottom piece of brass or similar relatively strong material. When such plastics cartridge cases are employed for live cartridges the relatively high forceful generation of heat caused by firing such cartridges will bring the cartridge chamber up to such temperature that the cartridge cases are liable to soften or melt when inserted into the chamber, which gives rise to the function faults called tear-offs or jammers.

Finally, it has been suggested to make cartridge cases with a wall comprising two layers, the outer layer being made of synthetic resin material, and the inner layer being made of light metal, for instance aluminium. The object of providing an aluminium case with an outer coating of plastics is to prevent the aluminium vnom adhering to the wall of the cartridge chamber. However, this cartridge case has the same drawback as mentioned above in connection with the plastic cartridge cases, i.e. that the plastic material softens or melts when the cartridge is inserted in the cartridge chamber, if the firearm has be-y come hot by shooting.

It has now turned out that it is possible to produce a satisfactory light metal cartridge case if a coating of synthetic resin is applied, not externally upon the light metal sleeve, but upon the inner side of such sleeve. If this internal plastics coating or casing is given suitable dimensions, the pressure of the powder gas will be taken up mainly by the plastics and only to a slight extent or not at all by the external light metal sleeve, and accordingly the latter will not be expanded more than permissible and will easily be pulled out of the cartridge chamber. On the other hand, the aluminium sleeve prevents instantaneous softening or melting of the resin material and prevents the resin material from adhering or sticking to the wall of the cartridge chamber even if it becomes soft. The internal sticking together of the two sleeves is of great advantage as regards to sealing against the gas pressure.

More particularly the invention relates to a cartridge case which comprises two sleeve members which are open at the rear end, the one being arranged co-axially in the other, the rear end of they outer sleeve member being attached to a tubular extension of a bottom piece of a suitable material, and the cartridge case according to the invention is characterised in that the external sleeve member is made of light metal and the internal sleeve member is made of artificial resin material or similar material.

It is an object of the invention to provide an improved f cartridge case or a cartridge'comprising such case.

It is also an object ofthe invention to provide acartridge case or a cartridge which is inexpensive toV manufacture.

It is a further object of the invention to provide a cartridge case or a cartridge comprising such case which is free from at least one of the drawbacks stated above in connection with the description of the prior cartridge cases.

It is also an object of the invention to provide an improved method for making cartridge cases or cartridges comprising such cases in an inexpensive manner.

In the accompanying drawings are shown ve embodiments of the invention, diagrammatically.

FIGURE 1 is an axial sectional view of a cartridge case of a first embodiment,

FIGURE 2 an axial sectional view of a cartridge case of a second embodiment,

FIGURE 3 an axial sectional view of a cartridge case of athird embodiment,

FIGURE 4 an axial sectional View of a cartridge case of a fourth embodiment, and f FIGURE 5 an axial sectional view of a cartridge case of a fifth embodiment.

In FIGURE 1 is shown a cartridge case comprising an outer sleeve member 1 of light metal and an inner sleeve member 2 of artificial resin material or material of similai properties, and a bottom piece 3. The rear end of the outer sleeve member is shrinked on atubular extension 4 of the bottom piece 3. The light metal sleeve member 1 encloses tightly the resin sleeve member 2. The rear portion of the inner sleeve member is arranged outside the extension 4, and in the extension is arranged a tightly fitting plastic cup. In the embodiment shown the sleeve member 2 is closed at its rearl end by an end wall which is very thin, at least at its centre, toprovide for easy penetration of ignition sparks passing from an ignition chamber in the rear side of the bottom piece through a bore in said bottom piece. The rear portion of the outer sleeve 1 encloses tightly the extension 4.

Each sleeve member 1 and 2 comprises a front extension providing a hollow portion, 5 and 6 respectively, the outer shape of such portion being substantially as the shape projectile or bullet. The extension 5 of the light metal sleeve 1 is closed at the front end and is, in a manner known per se, provided with at least two weakening lines or grooves which cross each other. The extension 6`of the resin sleeve member '2 is open at its front end. The'cartridge case is iilled with powder (not shown) in the usual manner. When the cartridge is tired the front end of the cartridge is torn up along the weakeningV ember Z is enclosed in the same manner as shown in [GURE 1.

The cartridge case shown in FIGURE 3 is also for a ank cartridge. The resin sleeve member 2 has no :tension 6.

In the embodiment shown in FIGURES 2 and 3 the ,ar end of the outer sleeve member 1 is rolled into an mular recess or groove 7 in the bottom piece 3. In le rear end wall of the inner sleeve member 2 is pro ded a central aperture 12 registering with a bore in the ottom piece 3.

FIGURE 4 shows a bottom piece 3 with a tubular ex- :nsion 4 having a relatively thick wall. The rear end f the inner sleeve member 2 has a stepped configuration nd extends into an annular internal recess in said tubutr extension 4, the rear end face of the sleeve member 2 ngaging a shoulder 14 on the extension 4. The rear nd portion of the inner sleeve member 2 provides a as trap. The rear end portion of the outer sleeve mem- `er 1 is rolled into two circumferential grooves 8 in the fottom piece 3 and its extension 4. The inner sleeve nember 2 has no extension 6.

In FIGURE 5 is shown a cartridge case in which the esin sleeve member 2 has a very heavy wall. The rear nd portion of the sleeve member 2 is recessed and a 'earwardly protruding end portion thereof projects into in annular recess in the tubular extension 4 of the botvom piece 3. An internal shoulder on the sleeve member E engages a shoulder 14 on the extension 4. Hereby ,here is provided an ecient gas trap. A hollow metal nember 81 provides a bullet-shaped end portion and has ,ts rear engaging the inner side of a narrow front portion :if the outer sleeve 1 and the front end of the internal sleeve 2.

The invention is not limited to the embodiments shown and described. The cartridge case can also be adapted for use in live cartridges. This is true as regards to the embodiments of FIGURES 1 through 5 provided that the bullet-shaped hollow end portion is replaced by a bullet.

I claim:

1. A cartridge case comprising a bottom piece having a substantially tubular extension and formed with an axial bore in its bottom, a light metal sleeve forming an outer shell and surrounding said tubular extension so as to constitute a tight it therewith, and an inner sleeve made of plastic and constituting a lining in said outer shell and extending into said tubular extension to also constitute a lining in the latter, said inner sleeve being closed at the end engaging said bottom piece by means of a bottom integral with said inner sleeve and weakened at a place opposite said axial bore in said bottom piece.

2. A cartridge case comprising a bottom piece having a substantially tubular extension, an inner annular shoulder in said tubular extension, a substantially cylindrical groove formed in said annular shoulder, a light metal sleeve forming an outer shell and surrounding said tubular extension so as to constitute a tight fit therewith, and an inner sleeve of plastic material lining said outer shell and extending into said tubular extension to abut against said annular shoulder, said inner sleeve having at its ends abutting against said annular shoulder a substantially cylindrical ange extending into said cylindrical groove.

References Cited in the file of this patent UNITED STATES PATENTS 2,842,057 Dunn July 8, 1958 FOREIGN PATENTS 522,888 Belgium Oct. 15, 1953 1,007,215 Germany Apr. 25, 1957 

